The overall objective of the clinical core is to provide the necessary resources to support the clinical components of the projects. This support will be divided into the following areas: 1. Identification of: a) families with high prevalence of dilated cardiomyopathy (DCM) (Project 1), and b) families with high prevalence of arrhythmogenic right ventricular dysplasia (ARVD)(Project 3.) 2. Characterization of subjects participating in projects 1, and 3 as to: a) basic demographics and symptomatic status b) detailed family pedigree c) presence or absence of echocardiographic criteria for DCM with 3 categories established: normal or unaffected, affected and indeterminate d) presence or absence of diagnostic criteria for ARVD with 3 categories established: normal or unaffected, affected and indeterminate. e) presence (or absence) of associated clinical conditions that reduce the odds of having DCM or ARVD 3. Coordinate patient recruitment, hemodynamic and functional evaluation, and procurement of myocardial biopsies for project 5. 4. Obtain and distribute human myocardial tissues for projects 3 and 5, including endomyocardial biopsy samples and explanted hearts.